1. Field of the Invention
The present invention relates to a flash lamp unit and a flash radiation device.
2. Description of the Related Art
Flash radiation devices have been used for treatment such as optical heat treatment by which, for example, only part of the surface layer of the article to be treated is selectively heated for a short time at a high temperature by irradiating the article with a flash, and low-temperature UV irradiation treatment by which the surface of the article to be treated is irradiated with intensive UV radiation, almost without heating the article.
Laser radiation devices such as solid-state laser radiation devices, gas laser radiation devices and flash lamps in which a rare gas, for example, xenon, krypton, or the like is sealed in a discharge container made from quartz glass (sometimes referred to as “rare gas flash lamps hereinbelow”) have been known as light sources for such flash radiation devices. However, because in the laser radiation devices, the flash is radiated at a single wavelength and the laser device for emitting photons per unit energy are very expensive, irradiation of the entire surface of the articles having a large treatment surface area is difficult. For this reason, rare gas flash lamps have been widely used.
However, in the rare gas flash lamps, a flash ignition state in which a flash is radiated within a short time is obtained by driving the lamp by supplying a flash power and also applying a high trigger voltage. However, in such flash lamps, the radiant efficiency representing the radiant quantity of flash related to the quantity of the supplied flash power is small. Moreover, the problem is that the radiant ratio of light (sometimes referred to hereinbelow as “long-wave UV light”) in a long wavelength region (wavelength 200 to 400 nm), which is considered to be effective for low-temperature UV irradiation treatment for conducting photochemical reactions, is especially small in the radiated flash.
The possibility of using a large power source unit for supplying the flash power and increasing the quantity of flash power supplied to the rare gas flash lamps has been studied.
However, in the rare gas flash lamps in a flash ignition state, the emission ratio of long-wave UV light generated inside the discharge container is small, whereas the emission ratio of light generated in a short wavelength region (sometimes referred to hereinbelow as “short-wave UV light”), which is absorbed by the materials constituting the discharge container, is large. Therefore, the quantity of emitted long-wave UV light increases as the quantity of the supplied flash power increases, which necessarily results in the increased quantity of emitted short-wave UV light. As a result, the problem associated with the flash radiation devices with a large supplied quantity of flash power is that rapid degradation occurs due to the absorption of a large quantity of short-wave UV light by the discharge container of the rare gas flash lamp.
Therefore, in the flash radiation devices, a plurality of gas flash lamps ignited by a comparatively low power have been used in order to obtain the flash radiation performance necessary for the treatment. As a result, the size of the flash radiation devices was increased and the cost thereof was raised.